TransGrid PSCR: Maintaining compliance applicable to secondary systems at Darlington Point

Market Network Service Provider
StageProject Specification Consultation Report
ConvenorAEMO NSP
Accepting submissions?Yes
Submissions close16/12/2020

TransGrid has recently published a Project Specification Consultation Report (PSCR) for maintaining compliance with performance standards applicable to Darlington Point substation secondary systems.

TransGrid has identified that the secondary systems at Darlington Point substation have reached a condition that reflects the end of serviceable life. As it is superseded by new technology at the manufacturer level and the existing technology becomes obsolete, spare parts become scarce and the ability of any primary asset connected to the substation to reliably operate will be at risk.

Darlington Point substation will continue to play a central role in the safe and reliable operation of the power system throughout and after the transition to a low-carbon electricity future. Located in the Riverina agricultural irrigation area inclusive of Leeton, the centre of the rice growing district in NSW, it forms part of the Southern New South Wales network which has been identified as an area of interest for new renewable connections.

Darlington Point substation is a customer connection point supplying the Essential Energy 132 kV network in the Riverina region and is the starting point for the 220 kV network supplying Far West NSW and interconnects to Victoria at Red Cliffs. 

Provision of redundant protection schemes to ensure the transmission system is adequately protected is a Network Performance Requirement under Schedule 5.1 of the National Electricity Rules (NER), therefore the condition issues affecting the secondary systems at Darlington Point substation must be addressed. If the failure to provide functional secondary systems due to technology obsolescence is not addressed by a technically and commercially feasible credible option in sufficient time (by 2022/23), the likelihood of not recovering from secondary systems faults and not maintaining compliance with NER performance requirements will increase.

Continued deterioration of the secondary systems at Darlington Point substation will accelerate the depletion of spares which will lead to a situation where TransGrid is unable to operate the secondary systems in accordance with clause 4.6.1 of the NER.  The proposed investment will enable TransGrid to continue to meet the standards for secondary systems availability set out in the NER, and to avoid the impacts of taking primary assets out of service. Consequently, it is considered a reliability corrective action under the RIT-T.

TransGrid considered three credible options that would meet the identified need from a technological and project delivery perspective. 

The implementation of Option 2, complete in-situ replacement of protection, market metering and control systems of secondary systems at the Darlington Point substation, is the most efficient technically and commercially feasible option at this draft stage of the RIT-T process. Option 2 can be implemented in sufficient time to meet the identified need by 2022/23, and is therefore the preferred option presented in this PSCR.

The estimated capital cost of this option is approximately $6.8 million +/- 25 per cent. TransGrid is the proponent of the proposed network project.

TransGrid welcomes written submissions on materials contained in this PSCR. Submissions are particularly sought on the credible options presented and from potential proponents of non-network options that could meet the technical requirements set out in this PSCR. Submissions are due on 16 December 2020.

In accordance with the requirements of the National Electricity Rules, a summary of the PSCR is made available on the AEMO website. A copy of the PSCR can be obtained from TransGrid’s website on the Regulatory Investment Tests page or by emailing

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